This invention relates to magnetron anodes and more particularly, but not exclusively, to magnetron anodes able to operate at relatively high power levels.
In one known magnetron design, a central cylindrical cathode is surrounded by an anode structure which typically comprises a conductive cylinder supporting a plurality of anode vanes extensive inwardly from its interior surface. During operation, a magnetic field is applied in a direction parallel to the longitudinal axis of the cylindrical structure and, in combination with the electrical field between the cathode and anode, acts on electrons emitted by the cathode, resulting in resonances occurring and the generation of r.f. energy. A magnetron is capable of supporting several modes of oscillation depending on coupling between the cavities defined by the anode vanes, giving variations in the output frequency and power. One technique which is used to constrain a magnetron to a particular operating mode is that of strapping. To obtain and maintain the pi mode of operation, which is usually that is required, alternate anode vanes are connected together by straps. Typically, two straps are located at each end of the anode or in another arrangement, for example, there may be three straps at one end of the anode and none at the other.
The present invention arose from a consideration of in what way the output power of a magnetron might be increased but the invention may also be used in applications where this is not a requirement.